The perspective of the economic analysis will be that of the NHS and personal social service. Costs to be obtained will include the costs of endoscopic treatment and continued endoscopic surveillance in both groups, as well as any additional intervention after the initial 8- month therapeutic phase of the trial. The costs of any salvage treatment at any stage will be included. We will test the validity and feasibility of administering the economic evaluation questionnaire (patient healthcare utilisation questionnaire and EQ-5D), examining the response rate achieved and levels of missing data. EORTC QLQ- C30 will also be tested to directly estimate QALYs using EORTC- 8D. Both EQ-5D and EORTC will be used to obtain the appropriate information for cost per QALY analysis in future economic evaluation. The economic analysis will inform sample size calculation and other necessary information to calculate the cost savings for future economic evaluation.